High-frequency apparatus



Feb. 21,-1950 Filed July 2, 1945 R. M. B KER ETAL 2,498,233

HIGH-FREQUENCY APPARATUS s shets-Sheet 1 WITNESSES:

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INVENTORS Faber/Hacker and E dwarfs/1 7. Wharf 66 ifizw wpze ATTORNEY Fb. 21, 1950 R. M. BAKER ETAL 2,498,233

HIGH-FREQUENCY APPARATUS Filed July 2, 19 45 3 Sheets-Sheet 2 WITNESSES: INVENTORS C Eober/MBa/(erand 7 a z. 24 64.46

ATTORNEY Patented Feb. 21, 1950 HIGH-FREQUENCY APPARATUS Robert M. Baker, Baltimore, and Edward. M. Wharfl, Arbutus, Md., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application July 2, 1945', SeriaLNo. 602,862

16 Claims.

Our invention relates to .coreless or air-cored transformers for use in induction heating systemspowered by a generator which .is. called upon to deliver high powers atfrequencies which may beas'much as 500,000; cycles per second, and frequently much more.

Our invention is more. particularly concerned with air-cored transformers and windings or-coils for'use in-- induction heating systems thatinclude an inductor coil-meansfor-heating a load. or work to a desired extent; at a desiredspeed. An: inductor coil-means must;v provide a sufliciently high magnetomotiveforce :at, the surface, of the metallicwork being. inductively heated, the, force oscillating at a frequency such: that the necessary heatwill be generated or induced in the Workin the required. time. This magnetomotive force is a. function of the. ampere-turns in the energized inductor coil-means. However, the number of turns provided: in an inductor coilmeans may'be limited by considerations of water-cooling, spacelimitations, size or form of the work beingheat-treated and other factors. Frequently, onlyone or a relatively few turns are the most that can bepracticably used. This meansthat currents ofhigh magnitude must flow through the inductor coil-means, making a low impedance in the'coil-means desirable.-

Tube-oscillator generators inherently have high internal impedance. For practicable operation of such devices, with high efliciency at-rated outputs, the apparent load impedance should' be of a value in the order of that ofthe; tube-oscillator generator. with our invention provides. a. means for "reflect,- ing the low impedance of the load,comprising the inductor coil-meansand' the work heated thereby, as a higher impedance at'the output connections'of the tube-oscillator generator.

An object of our invention is to, provide a simple variablepower-transformer for handling high frequency high-amperage-power.

A further object of our invention is to provide a compact transformer which can be associated with a. predetermined tube-oscillator generator; the transformer being. so constructed that the. ratio of its primary andsecondaryturns-can. be quite easily changed so that the tube-oscillator generator can efiiciently supply power to various kinds of loadsor inductor coil-means.

Still another object of our=invention is to pro.- vide ahigh-powered high-frequency. transformer constructed of; windings: whichare water-cooled,

A transformer in accordance the ratio of the turns of the; windings being adjustable without disturbing the path for the cooling water through the windings.

Additionalobjects, features, combinations, elements and. innovations of our invention will be discernible from the following description of. the present preferred. embodiment, when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a front elevational view, withparts broken away and in. section, of, a, transformer built ,inaccordance with-our invention;

Fig. 2 is aside elevational. view, with parts broken, away and. in section; and.

Fig. 3 is a horizontal. view with parts broken away and in section.

Referring, to the drawings, the transformer is indicated in its entirety. by the reference numeral 2.. It. comprises a continuous primary winding 4' of. a number of turns of continuous hollow. copperjtubing. Small circumferentiallyspaced insulating spacers 6 keep the primary turns apart, only affew spacersbeing shown. The primary winding 4' is substantially coextensive with and inside a thin'cylindrical member 8.made of an'insulating. material such as, for example, a laminated paper or clothimpregnated with a phenolic resin'andmolded'under heat and pressure. A form, of such insulation is sold under the trade-markMicarta, and all of the bar and plate members hereinafter'described are made of this material; unless otherwise specified,- but othersuitable insulation material maybe used.

A secondary isaround theoutside of the cylindrical'member 8, andcomprises a plurality of separate single-turn coils Ill, each comprising a flat solid copper strap havingfacing lower and upper ends l2- and M bent, as shown in Fig. 2, so asto beparallelto each other, but spaced slightly apart; The-coils l0 areparallelly arranged on the cylindrical'member 8, but. are edgewise spaced so as to be insulated: from each other. Each coil limhas'v acentral turn of. hollowrcopper'tubing l6 secured in good thermal contact with thestrap of. the; coil so: that: cooling liquid passing therethroughcan remove. heat generated in the coil. Theztubing his narrower thanthestrap and has ends l8. and 20 near thestrap. ends l2 and I4, respectively.

The secondary winding, comprising the coils l0, theprimary winding land: the. cylindrical member 8, are assembled and held together with asbestosyarnZZ. Several: of the small spacers 6 maybe U-Shaped; as indicatedin Fig. 2, for re ceiving and' positioning the tying yarn 22.

Afreme, which comprises a plurality of in gas es 3 sulating bars and plates giving it form and shape, carries the winding assembly. The primary winding 4 is provided with curved ends 26 and 28 clearing the cylindrical member 3 and having spaced tips 38 and 32 passing through holes in an insulating terminal plate 34 attached to the back of the frame. The tips and 32 may be provided with water-connections and electric power may be delivered to them in any suitable manner.

At the front of the frame, a plurality of rectangular copper blocks are symmetrically arranged, a separate block being provided for each end of the coils it. The blocks are carried by the frame on a side which is opposite to the terminal plate 34, the blocks being arranged in two horizontal rows, a lower row 38 and an upper row 40. The rows are vertically spaced apart for insulation, with mica insulation 42 in the space between rows. The several blocks in each row are also horizontally spaced apart for insulation, with mica insulation 44 between blocks. Consequently, each block is electrically isolated except for connections subsequently described. In the embodiment described, the rows 38 and 48 comprise blocks 46 which are generally alike except for the two diagonally opposite blocks 46 at the upper right and lower left corners of the block-assembly. These blocks 46' differ slightly from the others.

In order to position and help support the blocks, the frame is provided with lower and upper insulating plates 48 centrally spaced apart. Extending inwardly from the facing edges of the plates 48 are narrow parallel insulating bars 58 and 52, respectively, for receiving the rows 38 and of blocks therebetween. The bars 50 and 52 are kept in spaced fixed position by elongated bolt and nut means a l, passingthrough holes in the ends of the bars, and insulating spacer tubes 56.

The blocks are electrically connected to the coils Ill, and are provided with individual terminal'studs so that the blocks can function as terminals or terminal members.

Each terminal block 46 is formed with an inner cavity 58 which is open only at the inner face of the block, which is toward the opposite row; the terminal blocks d6" having similar cavities 58'. Each opening in the inner faces of the lower row 33 of the blocks is liquid-tightly closed by an individual strap-end l2; and each opening in the inner faces of the .upper row 40 is similarly closed by an individual strap-end M. Each block is slightly wider than the associated strap-end.

Each terminal block also has an opening in its back side, passing to its cavity, near its associated strap-end, for receiving an end of the copper tubing [6. The terminal blocks of the lower row 38 receive the lower ends E8 of the tubing I6, and the terminal blocks of the upper row 40 receive the upper ends 20 of the tubing It, the ends being abuttingly liquid-tightly secured to the blocks.

Each terminal block 46 is provided with a short pipe 60 which passes through an outer side of the block for communication with its inner cavity 58, the pipe being liquid-tightly secured to the block, with an end exposed. The pipes 60 secured to the lower row of blocks extend downwardly through spaced holes in the lower insulating bar 50, being held in position by lock nuts or other suitable means; and the pipes fill secured to the blocks of the upper row extend upwardly through the upper insulating bar 52 in a corresponding manner. However, the outer sides of the ter- 4 minal blocks 46' are solid, and are different in this respect from the blocks 46.

As shown in Fig. 2, the front or connection face of each terminal block 46 is also provided with a solid. copper terminal stud 62; while the front or connection face of each of the two blocks 46 is provided with a hollow copper stud 62 extending into the cavity 58 of the associated block. As is clear from Figs. 2 and 3, the connection faces of the blocks which receive the terminal connection means comprising the aforesaid studs, face in the same direction and lie in a plane. The studs 62 and 62 provide a means for electrically connecting the single-turn coils in in any selected manner through suitable interconnecting means which bridge selected terminal studs. We have shown the single-turn coils connected in series by bridging members or jumpers Bil comprising flat bars which are slotted or perfcrated so as to fit diagonally opposite studs of adjacent vertical pairs of blocks, as indicated in Fig. 1. However, it is quite evident that the coils to may be connected in parallel by a suitable jumper spanning and interconnecting all the top studs and a suitablejumper interconnecting all the bottom studs. Different series-parallel combinations of the coils can be obtained in an obvious manner by using other kinds of jumpers, so that the ratio of a number of primary turns to secondary turns of the transformer can be easily changed. If desired, some of the single-turn coils may be left open circuited.

In high-power high-frequency apparatus of a type described, it is desirable to provide means for cooling the current carryingv parts, and in accordance with our invention we provide a fixed conduit system through which cooling water may be caused to flow for cooling the secondary, irrespective of the manner in which the coils are electrically connected. In other words, it is not necessary, in our invention, to, in any way change the cooling system when the electrical connections between the coils are altered by changing the manner in which they are bridged by any suitable jumpers. To this end, insulating hoses 66, of rubber or other insulating material, are connected between separate pairs of adjacent pipes fill of the lower rowof terminal blocks 46, and similar insulating hoses 68 are provided interconnecting the pipes 50 of each pair of adjacent blocks 45 in the upper row. Clamps or other means may be used to clamp or fasten the hoses Water-tightly to the extending ends of the pipes 60. In the lower row of blocks, a hose 55 connects the first and second blocks 45 from the right, and the third and fourth blocks 46; while in the upper row, a hose 68 connects the first and second blocks 45 from the left and the third and fourth blocks 35. The hoses 66 and 68 are inside the frame and preferably as short as conveniently possible.

In the preferred formof our invention, the two diagonally opposite terminal blocks it are not provided with holes in their 'outer'sides for receiving hoses. Instead eachlug 62 on the front sides of these blocks is hollow, communicating with the associated cavity 58 of the associated block 36. These lugs 62 constitute water inlet and water outlet means to which hoses or pipes may be connected leading respectively to a source of water supply and to an outlet or drain for the spent water. One or both connections to these studs 62' are conveniently of insulating hose, and are secured to the ends of the studs in a manner to permit a slotted or forked connector to be received bythe studs, as schematically shown in ,i 'ig. 2,lWh81'eLJ1;he. nut has, room v to ;move .on .rthe stud afterzaslotted connector 12 .is slipped on.

:Wihemwater:isrsuprilied towthe. lug 62' of one of the copper terminal blocks 46', it is evidentthat 'isuch water wilrfirstiiow into the cavity 58 of :thiszblock'. =Assume'it to'be the block insthe lower row 38. Theiwater will-then flow into the lower tendv [8i Of5t1 lelcopper;tubing l5 secured to this :block, through this. :copper: tubing to the. upper ,end '2ll::.thereof,.=.and intoxthe c'ayitys58 of the first left terminal block 46 of the upper row 40,

-;';th-is.abloclr 45 .beingimmediately above the waterreceivingxblock 46 of the row 38; Thewater then .passes upwardly through the associated pipelifl into a hose 68 from where it is delivered into the cavity 58of-the-second left block 4B ofthe upper rovvl lll. :The'.water.;passes through thisblockand through; thermipingl6 associated therewith to the immediately underneath block 46 of the row 38. .The-water thenwpasses through a lower hose 66 into the cavity of the next adjacent, or third from left, block 46 of the row 38, and in the obvious manner the-water-flow path continues along course in which the water flows successively through each of the tubings l6 and the terminal blocks, coming out at the right-hand block 46 of the upper row 40.

With a thin cylindrical member 8, thewater :circulating through the primarycan augment the cooling of the secondary; coils l-O by the water circulating in the tubing [6.

While we have describedlourinvention in a preferred :embodiment, it is obvious that athe ytea'chingsrand principles thereof may be incorporated in :other embodiments and in similar ap- .paratus.

We claim as our invention:

1. Apparatus of a type described for high frequency use, comprising a support, a plurality of individual insulated hollow terminal blocks carried by said support, each block having an inner cavity, a plurality of separate conducting straps, each bent along a curve, each strap having ends secured to separate terminal blocks, a hollow tube secured to each strap in thermal relation therewith, means for providing a continuous duct from the cavity of a first of said terminal blocks through a hollow tube secured to a strap, to the cavity of a second of said terminal blocks, and hollow insulating connections connecting the inner cavities of predetermined terminal blocks, whereby to provide a conduit system for the flow of cooling fluid through said terminal blocks and said hollow tubes.

2. Apparatus of a type described for high frequency use, comprising a support, a plurality of individual insulated hollow terminal blocks carried by said support in spaced rows, each block having an inner cavity, a plurality of separate conducting straps, each bent along a curve, each strap having ends secured to separate terminal blocks, a hollow tube secured to each strap in thermal relation therewith, means for providing a continuous duct from the cavity of a first of said terminal blocks through a hollow tube secured to a strap, to the cavity of a second of said terminal blocks, hollow insulating connections connecting the inner cavities of predetermined terminal blocks, whereby to provide a conduit system for the flow of cooling fluid through said terminal blocks and said hollow tubes, said terminal blocks having connection faces facing in the same direction, and detachable short conducting members bridging certain of said faces of said terminal blocks.

p3asApparatus of atypeldescribed comprising a support, a plurality of individualhollow: terminal rblocksicarried byisaid support ina pair of spa'ced rows, with :insulation' between said rows and between the-terminal blocks of a row, .a'plurality of parallelzsingle-turn conducting straps in edgevwise spaced relation, the ends of said straps being abuttingly; secured to separate sides of said ter- ;.minal: blocksp-andwmeans for cooling said straps and terminalblocks; comprising :a plurality of :individual- :metallic: tubing, each: secured to "one .of'said straps; and duct-paths comprising insulatyingshosesr between pairs of said'terminalxblocks.

- 4."Apparatustof a .type describedcomprising "a support, a plurality of individual terminal "blocks carried by saidsupport in-a pair of spaced rows, with insulation between said rows. and between the terminal blocks of a row, a plurality of parallel 1 single-turn :conducting straps in edge- Wise spaced arelatiorrethe ends of said straps: be-

,ing abuttingly secured to separate sides of said terminal blocks, means for cooling said straps 'comprisinga plurality of individual metallic tubing, each; secured to oneof said straps,-and-'insulating hoses therebetween, and a plurality of "conducting bars bridging terminal blocks in different rows,- each ofsaid insulating hoses-being associated with terminal blocks in the same row.

5.."Anmairecored transformer comprising a frame; aneinner primary, aseoondary comprising a plurality ofseparate straps around said .primary, :a plurality of insulated terminal blocks carried at aside of isaidifra-me each terminal block having a cavity-opening into aaside'of the associatedrterminal block, an end of :a strap being :secured to such side of a blockfordiquid tightly closing the associated cavity, individual metal cooling tubing for each of said straps, an end of such tubing being associated with an end of a strap, and communicating with the cavity of the associated block, means along a certain side of said terminal blocks for electrically interconnecting said terminal blocks, and insulating hose connections connecting the cavities of predetermined terminal blocks, the cavities termihating at other sides of said terminal blocks, whereby to provide a conduit-system for the flow of cooling fluid through said terminal blocks and said metal tubing.

6. A high-frequency transformer comprising a frame having a plurality of sides, an insulating hollow cylindrical member, a primary winding along the inside of said cylindrical member, a plurality of separate secondary coils around the outside of said cylindrical member, said coils comprising straps spaced edgewise, a hollow metal tube secured in good thermal contact to the outside of each of said straps, a plurality of insulated hollow terminal blocks on one side of said frame, each separately receiving an end of one of said secondary coils and an end of the associated metal tube, with the last in communication with the cavity in the associated block, and hoses for interconnecting the cavities of said terminal blocks.

'7. Apparatus of a type described comprising a frame, a pair of rows of hollow terminal blocks carried by said frame, with insulation between the terminal blocks of a row and between rows, a plurality of separate coils arranged axially, each coil having strap-ends having faces conductively abuttingly secured to terminal blocks in different rows, each coil comprising cooling means in the form of tubing having ends connected to the cavities of terminal blocks to which the coil ends are conductively secured, and insulating hoses 7 connecting the cavities of adjacent terminal blocks in the same row.

8. The invention of claim 7 characterized by a pair of diagonally opposite blocks in said rows being provided with hollow connections for conveying Water to and from said apparatus.

. 9. Apparatus of the type described comprising a support, a plurality of hollow terminal blocks insulatedly carried by said support, the cavity of each block extending to a side of the block to form an opening thereat, 'a winding comprising a plurality of turns of separate conducting straps, said conducting straps having flat end-portions conductively secured to said terminal blocks and closing said openings, and means for conducting cooling fluid to and from said. blocks, the last said means including hollow portions associated with said straps for cooling them.

10. An invention including that of claim 9 but characterized further by having means for selectively electrically connecting said terminal blocks.

11. Apparatus of the induction type comprising a plurality of individual hollow terminal blocks arranged in a pair of spaced rows, with insulation between said rows and between terminal blocks of a row, a plurality of parellel single-turn conducting straps in edgewise spaced relation, the ends of said straps being abuttingly secured to separate sides of said terminal blocks, and means for cooling said straps and terminal blocks comprising a plurality of individual tubing, each secured to one of said straps, and a ductpath comprising an insulating hose between at least two of said terminal blocks.

12. Apparatus in accordance with that defined in claim 11 but further characterized by each of 8 said terminal blocks having a connection face, and electrical connection means at each of said faces, all of said faces facing in the same direction.

13. Apparatus in accordance with claim 12 but further characterized by each of said connection faces lying substantially in a plane.

14. Apparatus in accordance with claim 1 but further characterized by said terminal blocks having connection faces lying substantially in a plane.

15. Apparatus in accordance with claim 3 but further characterized by said terminal blocks having connection faces lying substantially in a plane.

16. Apparatus in accordance with claim 4 but further characterized by said terminal blocks having connection faces lying substantially in a plane.

ROBERT M. BAKER. EDWARD M. WHARFF.

REFERENCES CKTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,145,551 Burke July 6, 1915 1,394,044 Stephens Oct. 18, 1921 1,789,229 Gebhard Jan. 13, 1931 1,791,934 Northrup Feb. 10, 1931 1,989,376 Northrup Jan. 29, 1935 2,181,899 Kennedy -1 Dec. 5, 1939 2,341,943 Ogden Feb. 15, 1944 2,366,290 Rudd Jan. 2, 1945 

